1. Field of the Invention
The present invention relates to a thermoelectric generator for a vehicle, and more particularly, to a thermoelectric generator for a vehicle including a thermoelectric generating unit which is mounted between an exhaust gas inlet pipe through which an exhaust gas flows in and an exhaust gas outlet pipe through which the exhaust gas is discharged, has a coolant inlet formed on one side and a coolant outlet formed on the other side thereof, and is formed by assembling a plurality of unit modules each having thermoelectric elements.
2. Description of the Related Art
In general, a thermoelectric generator refers to an apparatus which obtains electrical energy by using a potential difference generated between a heating element and a cooling element when a temperature difference is applied to both ends of the heating element and the cooling element. Typically, the heating and cooling element are made of metals or semiconductors. As such, heat may be directly converted into electricity without mechanical operations.
Thermoelectric generator are often applied to exhaust gas equipment of industrial boilers, and power supply facilities in remote areas, and in recent years, they have begun to be applied to waste heat utilization systems for waste incinerators, geothermal power generation, ocean temperature difference power generation, or the like.
Meanwhile, since the efficiency of an engine driving alternating current generator (also called an alternator), which supplies electrical power within a vehicle to charge the battery, is only operating at about 33% efficiency, and the shaft power of the alternator should be increased as electric power consumption of the vehicle is increased, as the loss of the shaft power is increased, fuel consumption becomes increases, and an increase of pollutants are discharged due to the high fuel consumption.
The amount of energy that is required to operate the alternator changes based on a driving state of the vehicle and the amount of electrical power being consumed by the vehicle. Therefore, thermoelectric generators which collect exhaust heat from an engine have begun to be added to vehicles.
The thermoelectric generator in a vehicle typically includes a heating unit for performing heat exchange/transfer between the exhaust gas and a high temperature end of a thermoelectric module. This thermoelectric module often includes a plurality of thermoelectric semiconductors, a cooling unit for cooling a low temperature end of the thermoelectric module, and an exhaust heat recovery apparatus. The thermoelectric generator converts thermal energy, which is obtained from exhaust heat of the engine, into electric energy.
FIG. 1 is a schematic view illustrating a concept of a thermoelectric module used in a thermoelectric generator. A thermoelectric module is a circuit manufactured so that an electric current flows by thermoelectromotive force generated by connecting p-type and n-type conductors or semiconductors and setting a high temperature heat source at one side and a low temperature heat source at the other side. Typically, each thermoelectric module may output about 2 W to 4 W.
However, it is necessary to maximize a temperature difference between the heating unit and the cooling unit to increase the amount of power generated by the thermoelectric module, but because the structural efficiency of the heating unit and the cooling unit is currently poor in the thermoelectric generator for a vehicle of the related art like the one shown in FIG. 1, the temperature difference between the high temperature end and the low temperature end is smaller than what is desirable.